It strikes me that for capsize recovery your goal would be the highest flow rate you can handle given your electric system.
For example, this 4000GPH bilge pump would draw 15A.
https://www.fisheriessupply.com/johnson ... ilge-pumpsThe same site also lists a 2200 GPH model for half the flow rate at half the current draw.
In principle, you could use other kinds of submersible pumps, but bilge pumps are convenient. Not only are they submersible by definition, they're designed for 12V systems. You might need to mount it to a base with a handle because the pump itself is normally mounted in the bilge, but here you'd want to be able to place it temporarily. A base would keep the pump upright and the hose and wiring can be lead up along the handle. You can even mount a float switch on the base, to shut off the pump before it runs dry.